The present invention is, as indicated hereinabove, a continuation-in-part application of copending application Ser. No. 660,383. That application discloses certain 6-carboxy flavone compounds which can carry one or more substituents on the phenyl ring thereof. While the generic formula of that application encompasses compounds wherein the phenyl ring carries an alkyl substituent and an alkoxy or alkenyloxy substituent, the only flavone compound specifically disclosed which has a phenyl ring carrying two substituents is the compound 6-carboxy-2', 6'-dimethoxyflavone, one of the compounds of Example 1 of application Ser. No. 660,383. The compounds which are claimed in the present application, however, unexpectedly exhibit greatly increased activity levels as compared to the compounds specifically disclosed in the copending application Ser. No. 660,383.